Atletico Mineiro star Ronaldinho is an injury doubt for December's Club World Cup after suffering a torn groin muscle.
The Copa Libertadores champions will likely be placed as second favourites behind UEFA Champions League holders Bayern Munich for the tournament, which is being held in Morocco for 2013.
However, they could have to do so without one of their key players, with the former Milan and Barcelona star likely to remain sidelined for the next three months.
Club medical director Rodrigo Lasmar told Atletico's official website: "Ronaldinho felt pain in the left thigh adductor region and, after clinical examination and imaging, we confirmed that he had a total rupture of adductor muscles of the left thigh.
"He's in intensive care and we await developments. The player is in the care of our physiotherapy department and every effort will be made to ensure that he recovers as soon as possible.
"We're always very careful in talking about time because there is no rule, there are many factors involved that can influence the term.
"It's a serious injury, but recovery time is short, it revolves around two and a half months, three months, three and a half months.
"The big question is whether he will be able to play the Club World Cup. We must believe in that possibility.
"A major effort will be made so that it is available to the coaching staff. It is a challenge, but the athlete is motivated, we're motivated and there is no restriction, the treatment can be done full-time."
MRI images displaying Ronaldinho's injury had been leaked to the Brazilian press with those actions condemned by Atletico in a separate statement.
Lasmar wrote: "The leak of these pictures is absurd and brings outrage as it is a severe breach of faith and conduct.
"Atletico's medical department always respected the privacy of athletes, safeguarding the rights guaranteed by the code of ethics of the profession.
"The club will take the appropriate steps in order to clarify responsibilities in relation to the subject."
|Kiessling calls for Leverkusen response|
|Matuidi: Cavani on par with Ibrahimovic|
|Yeboah set to join Borussia Monchengladbach|
|Rooney a ´chance´ to face West Ham|
|FIFA Club World Cup Preview: Bayern Munich v Raja Casablanca|
|Benzarti praises ´extremely talented´ Raja Casablanca|
|Ranieri unsure over Falcao return|
|Coupe de La Ligue Wrap: Cavani leads PSG to dramatic win|
|Copa del Rey Wrap: Real Madrid through as Sevilla crash out|
|Tottenham job appeals to Sherwood|
|Sherwood gutted after defeat|
|Hughes: United worthy winners|
|Moyes pleased to see United weather storm|
|Allardyce hails West Ham fight|
|Coppa Italia: Juventus 3 Avellino 0|
|Manchester clubs kept apart in League Cup semi draw|
|League Cup: Tottenham 1 West Ham 2|
|League Cup: Stoke City 0 Manchester United 2|
|FIFA Club World Cup: Raja Casablanca 3 Atletico Mineiro 1|
|Sheffield Wednesday, Wigan abandoned due to heavy rain|
|United face anxious Rooney wait over injury|
|Messi making good progress|
|Ramos ban overturned|
|Osvaldo charged by FA|
|In-demand Ince offered new Blackpool deal|
|Molde confirm Solskjaer approaches|
|Kramer keen to continue home record|
|Rodgers: Henderson has potential to get even better|
|Ruiz on Anderlecht´s radar|
|Swansea, Hull fined by FA over player behaviour|
|Leeds keen on re-signing Gradel|
|Leverkusen announce Ryu deal|
|Ribery named Bundesliga Player of the Year|
|Moyes: No Zaha interest|
|Barcelona, Real Madrid in European Commission investigation|
|Basel: No Tottenham approach for Yakin|
|Chelsea set for Guarin bid, agent claims|
|Lewandowski has Dortmund goal concerns|
|Pogba, Pirlo will not sign before Christmas, says Marotta|
|Guardiola convinced to join Bayern after ´meat´ and greet|
|Martinez: Everton seen as a ´perfect´ loan destination|
|Anderlecht ´perfect´ for Defour, says Van Holsbeeck|
|Watford appoint Sannino|
|Sakho feels ´lucky´ to play with Suarez|
|Lippi: Too many teams competing in Club World Cup|
|Moyes ´told Welbeck to learn from Rooney´|
|I would kill myself over match-fixing, says Gattuso|
|Hughes dismisses calls for Januzaj protection|
|Aguero ´could miss up to two months´|
|Guardiola lauds Ballon d´Or nominee Ribery|
|Liverpool open Suarez contract talks|
|Copa del Rey Wrap: Barcelona, Levante cruise through|
|A-League Preview: Derby date beckons for winless Heart|
|Pearson upbeat despite Leicester defeat|
|Poyet urges Sunderland to build on Chelsea win|
|Mourinho rues missed chances|
|Pellegrini proud of professional Manchester City|
|Bayern on another level, says Beckenbauer|
|League Cup: Sunderland 2 Chelsea 1 (aet)|
|League Cup: Leicester City 1 Manchester City 3|
|FIFA Club World Cup: Guangzhou Evergrande 0 Bayern Munich 3|
|Zenit and Olympiacos punished with partial stadium closures|
|Sherwood wants positive reaction|
|Ancelotti expected La Liga title fight|
|Moffat charged over betting allegations|
|Wilson appointed at Barnsley|
|Wilshere charged by FA|
|Gattuso determined to clear his name|
|Moyes slams sacking culture|
|Mackay refuses to resign despite owner criticism|
|Redknapp reluctant to take Taarabt back|
|Amat pleased with development|
|Hughes optimistic of League Cup progression|
|Perez: No bids for Di Maria|
|FIFPro demand transfer system overhaul|
|Edwards sacked by Perth Glory|
|Allardyce not fearing the sack|
|Howson commits to Norwich|
|Tevez resigned to Argentina snub|
|SFA uphold Butcher´s one-match ban|
|Zapata rules out United switch|
|European Ombudsman calls for action on Spanish tax complaint|
|Albrighton eyes new Villa deal|
|Bale to miss Copa del Rey clash with ´small injury´|
|Pardew will bide his time in January|
|Kreuzer confident of Hamburg improvement|
|Van der Sar: Moyes can turn United around|
|Maradona backs Ronaldo for Ballon d´Or|
|Tottenham warned off Klinsmann|
|Costa Rica Primera Division: Alajuelense 0 Herediano 0|
|Lyon wary of Chornomorets Odesa|
|Guardiola talks up Lippi, Evergrande|
|Chile Primera Division Wrap: Chile, Deportes Iquique reach final|
|Garcia laments defensive mistakes|
|La Liga: Real Valladolid 3 Celta Vigo 0|